Older chemistry sets used to come with potentially dangerous, occasionally radioactive, compounds. The Chemical Heritage Foundation has dug into their vaults for some of those vintage experiments. - some of which were targeted towards students and youth.

While you may have never heard of a toroidal vortices, you are most assuredly familiar with one example - the smoke ring. Watch stunning rings be produced by dolphins, humpback whales, volcanoes, and even hydrogen bombs.